I. Field of the Invention
The present invention relates generally to medical instruments and, more particularly, to an endoscope.
II. Discussion of Related Art
Laparoscopic surgery has enjoyed increasing acceptance, particularly for surgery involving the abdominal cavity. In such surgery, one or more incisions are made through the patient""s skin. Thereafter, various medical instruments, including endoscopes, are inserted through the incisions and into a body cavity, such as the abdominal cavity.
In order for the surgeon to see into the abdominal cavity, the surgeon typically uses an endoscope which is inserted through a cannula and into the abdominal cavity. The previously known endoscopes typically comprise an elongated tube having one or more fixed lenses. These lenses provide an optical view of the interior of the body cavity to an eyepiece or other display means accessible to the surgeon outside the body. Illumination for the endoscope is typically provided by optical fibers which extend along the length of the endoscope and form a ring around the outer periphery of the free end of the endoscope. The opposite ends of the optical fibers are connected to a light source.
These previously known endoscopes, however, have all suffered from a number of disadvantages. Perhaps the most significant disadvantage of these previously known endoscopes is that, since the optical lenses are fixed within the endoscope, the angular magnification for the endoscope remains constant. Typically, these previously known endoscopes utilize lenses which provide low or macroscopic magnification (hereafter collectively referred to as macroscopic magnification) within the body cavity so that a relatively wide field of view of the body cavity is obtained.
In many situations, however, it would be desirable for the endoscope to provide microscopic magnification of organs contained within the body cavity. For example, in certain situations where cancerous growths within body organs are suspected, the macroscopic magnification provided by the previously known endoscopes is insufficient to examine the organ tissue in sufficient detail to determine whether the tissue abnormality is cancerous or benign. As a result, it has been necessary for the surgeon to perform a biopsy of the tissue, and, in many cases entirely remove the tissue, for subsequent pathological examination outside the body.
The removal of biological tissue from the body and subsequent pathological examination outside the body suffers from two important disadvantages. First, in the event that the organ abnormality is benign, the biopsy and possible removal of the entire organ from the body results in unnecessary harm and even loss of organ function to the patient. Second, since the subsequent pathological examination of the body tissue oftentimes occurs long after the end of the operation, in the event that the pathological examination reveals a cancerous growth within the body tissue, it is oftentimes necessary for the surgeon to re-enter the body cavity and remove additional body tissue in an attempt to completely eradicate the cancer. This disadvantageously, however, subjects the patient to a second operation.
There have been previously known endoscopes which utilize movable lens groups to vary the image between microscopic and macroscopic magnification. These prior devices, however, have used complex systems for moving the lenses which disadvantageously increase the overall diameter of the endoscope.
The present invention provides an endoscope for use in laparoscopic surgery which overcomes all of the above-mentioned disadvantages of the previously known devices.
In brief, the endoscope of the present invention comprises a housing which is adapted to be held by a robotic arm or manipulated by hand by the surgeon or other medical personnel. An elongated lens tube has one end secured to the housing. An elongated tubular stage is then removably secured over the lens tube and the stage and lens tube are adapted for insertion into the body cavity.
Unlike the previously known endoscopes, in addition to one or more fixed lens groups, at least one and preferably three lens assemblies are longitudinally slidably positioned within the lens tube. Drive means, such as stepping motors, contained within the housing are mechanically connected to each movable lens assembly in order to longitudinally displace the lens assemblies within the lens tube. In doing so, the optical magnification achieved by the lens assemblies in the endoscope can be varied between macroscopic magnification and microscopic magnification. Macroscopic magnification is utilized to provide an optical view for the surgeon of a relatively wide area within the body cavity while, conversely, microscopic magnification is utilized to examine target body tissues.
The stage is also longitudinally movable with respect to the lens tube between an extended and a retracted position by drive means contained within the endoscope housing. A transparent optical window is disposed across the free end of the stage and this window is in alignment with the optical system of the lens tube. Liquid, preferably a saline solution, is contained between the end of the lens tube and the window on the stage to eliminate refractive errors between the lens tube and the stage.
The lens contained within the lens tube and housing is preferably a confocal lens system. As such, with the stage window positioned against the target body tissue, longitudinal displacement of the stage relative to the lens tube provides a microscopic image through the endoscope at different tissue depths.
The ability to provide microscopic imaging of internal organs permits in vivo pathological examination of internal organs without the necessity of a biopsy. Furthermore, to enhance the imaging of the microscopic images, preferably infrared radiation is provided directly through the lens tube and stage window to the tissue. Any conventional source of infrared illumination can be utilized, but preferably a diode laser is utilized.
In the preferred embodiment of the invention, the optical images through the endoscope are digitized and coupled as an input signal to a computer system. The computer system, in turn, communicates the digitized images via a network and/or telephone lines to a pathologist remote from the patient. Consequently, the pathologist is capable of viewing the images through the endoscope on a real-time basis. Since the endoscope of the present invention enables real-time pathological examination of suspect tissue, unnecessary biopsies and/or organ removal is prevented.
Unlike the previously known endoscopes with movable lens groups, the present invention utilizes small strands extending through and/or connected with the lens groups in the endoscope so that longitudinal displacement of this strand longitudinally displaces the lens group associated with the strand. These strands advantageously do not increase the overall diameter of the endoscope.
A better understanding of the present invention will be had upon reference to the following detailed description, when read in conjunction with the accompanying drawing, wherein like reference characters refer to like parts throughout the several views, and in which:
FIG. 1 is a perspective view illustrating a preferred embodiment of the present invention;
FIG. 2 is an exploded view illustrating a preferred embodiment of the present invention;
FIG. 3 is a perspective diagrammatic view illustrating a portion of the preferred embodiment of the present invention and with portions removed for clarity;
FIG. 4 is a longitudinal sectional view of a portion of the preferred embodiment of the present invention;
FIG. 5 is a longitudinal fragmentary sectional view illustrating a portion of the preferred embodiment of the present invention;
FIG. 6 is a view similar to FIG. 5, but illustrating the stage in a different position;
FIG. 7 is a fragmentary side diagrammatic view illustrating a portion of the preferred embodiment of the present invention;
FIG. 8 is a longitudinal sectional exploded view illustrating the preferred embodiment of the present invention;
FIGS. 9A-9C are side diagrammatic views illustrating the lens magnification of the preferred embodiment of the present invention; and
FIG. 10 is a flow chart illustrating the operation of a preferred embodiment of the present invention.